Nucleic Acids

  • Created by: Lucillee
  • Created on: 27-04-17 13:50

Nucleic Acids

Two types of nucleic acids:

1. Deoxyribonucleic acid (DNA)

2. Ribonucleic acid (RNA)

DNA carries genetic code (synthesis of polypeptides) and is self-replicating

RNA assists the functioning of DNA

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Nucleotide Structure

Nucleotides: subunits of nucleic acids

Each nucleotide has:

  • a pentose sugar (deoxyribose or ribose)
  • a nitrogenous base (deoxyribonuleotides: adenine, guanine, cytosine and thymine / ribonucleotides: adenine, guanine, cytosine and uracil)
  • a phosphate group (attached to pentose sugar)
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Nucleic Acid Structure

  • Nucleotides are joined by condensation reactions to form phosphodiester bonds (between phosphate of one nucleotide and the C3 of the pentose of the other nucleotide)
  • The polynucleoide strand has a free 5-end (phosphate attached) and a free 3-end
  • DNA has two anti-parallel strands
  • Bases are joined by hydrogen bonds, improving stability (A and T, G and C (base pairing))
  • Nucleotides join at slight angles, forming the double helix
  • RNA molecules are single stranded and much shorter than double stranded DNA and RNA has no base pairing
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